Afamily consumes 2.5 gallons of milk per week. how many liters of milk do they need to buy for 1 week?

there is none because earth is stationary and flat.

weight of any object is given by

w = m*g

where m is mass of the object and g is the acceleration due to gravity.

for earth the value of g is 9.8 m/s^2 so

w=117.6 n m=12 g=?

117.6=12g => g=9.8 m/s^2

which is the force of gravity on earth.